The present invention relates to methods and apparatus for unwinding web materials. More particularly, the invention pertains to methods and apparatus for unwinding web materials having a plurality of narrow lanes.
The manufacture of products such as disposable absorbent articles involves the use of narrow webs of flexible material. Such flexible materials can include, by way of illustration, nonwoven materials, elastic materials, adhesive tapes, polymeric films, release paper, mechanical fastening materials or the like. Due to their narrow widths, these flexible materials and others of this type present special handling difficulties.
For example, narrow web materials are sometimes processed in the form of planetary wound rolls, often called xe2x80x9ccookie rollsxe2x80x9d or xe2x80x9ccookiesxe2x80x9d where the narrow web material is wound directly upon itself to form a narrow roll. Given the width of the web material, however, these very narrow rolls can be unstable and tend to warp or fall apart when lifted. Support members can be used to protect the cookie from distortion or damage, but that introduces a new structure and increases the processing cost of the web material and the cost to change rolls. Moreover, individual cookie rolls have a relatively short run time, which undesirably leads to frequent roll changes.
To circumvent these difficulties, narrow web materials can be level wound. By oscillating the narrow web material back and forth across the roll during winding, the level winding process yields a stable roll form that resists damage. Again, however, the level winding process can add significant expense to the web material.
Certain web materials such as molded hook fasteners have been formed into wide intermediary tapes. These wide tapes include strips of hook material separated by splitting channels or perforations. Processing of such wide tapes has to date required simultaneously separating the strips of hook material using specialized equipment such as splitting combs or slitting blades. Not only is such specialized equipment expensive to obtain and operate, but its use is practical only for converting operations that can accommodate simultaneous processing of multiple strips.
In view of these deficiencies and limitations with conventional manufacturing operations, it would be desirable to have improved methods and apparatus for unwinding narrow web materials.
In response to the above-referenced deficiencies and limitations, a new method of unwinding a web material has been discovered. The method includes providing a roll of web material that defines a plurality of integral lanes with a separator disposed between the lanes, and tearing the web material along the separator to disconnect at least one lane from at least one other lane. The selected lane is unwound from the roll while continuing to tear the web material along the separator and maintaining the other lane on the roll.
With this method, the parent roll can contain a relatively wide web of material that consists of a plurality of lanes of web material. The parent roll can provide a high degree of roll stability to minimize damage to the material during handling and storage operations. The individual lanes of web material can be unwound sequentially from the parent roll. In this way, only the number of lanes that are required for immediate processing need to be unwound. The remainder of the lanes can remain wound on the parent roll. This method can provide a stable roll form for delivering narrow lanes of material, without requiring an additional slitting operation and without the added expense of level winding or support members.
It is especially significant that the web material includes separators that enable the web material to be torn into individual lanes or groups of lanes. The terms xe2x80x9ctornxe2x80x9d and xe2x80x9ctearingxe2x80x9d in the context of this application mean that at least one lane of the web material can be or is separated from at least one other lane of the web material without using a cutting or slitting device. Separators can comprise any structure or treatment that causes the web material to tear into distinct lanes. In particular embodiments, suitable separators can comprise perforated regions, intermittently cut or slit regions, score marks, reduced thickness or reduced integrity regions, including splitting channels, creased regions, added elements or treatments that direct or limit tearing to a defined area, molded or embossed indentations, or the like. Perforation or scoring devices can be incorporated into the web production process or as a later converting step for the web material. The perforation or scoring devices can continuously or intermittently perforate, cut, or indent the web material. Alternatively, for molded web materials the material can include integral, molded-in splitting channels. The splitting channels can comprise generally longitudinal regions that have a relatively lower basis weight or less durable structure, so that the lanes can be separated along the splitting channels. Forming the web material so that it can be torn without the use of a cutting or slitting device simplifies the unwinding operation and reduces equipment and maintenance costs.
The manner in which the remaining lanes of web material are maintained on the parent roll will depend to some extend of the nature of the web material. In most cases, it may be sufficient to hold the leading ends of the remaining lanes of web material against the roll. Various means can be used to hold the remaining lanes in place, including but not limited to items such as tape, clips, clamps, bands, adhesives, cords, covers, or the like.
The present method is particularly suited for narrow webs of flexible material. The individual lanes can have any desired width, such as about 5 cm. or less or about 2 cm. or less. The parent roll on the other hand can be relatively wide and can contain any number of lanes depending upon the width of the lanes. For lane widths on the order of 2 cm., for example, the web material on the parent roll can comprise 2 or more lanes, particularly 4 or more lanes, more particularly 8 or more lanes, such as 10 to 60 lanes or more.
The present method can be used for unwinding a variety of flexible materials, such as nonwoven materials, elastic materials, adhesive tapes, polymeric films, release paper, mechanical fastening materials, or the like. Mechanical fastening materials can comprise interlocking geometric shaped materials, such as hooks, loops, bulbs, mushrooms, arrowheads, balls on stems, male and female mating components, buckles, snaps, or the like. In particular embodiments, the mechanical fastening materials comprise hook-and-loop fastening elements. Loop type fasteners typically comprise a fabric or material having a base or backing structure and a plurality of loop members extending upwardly from at least one surface of the backing structure. The loop material can be formed of any suitable material, such as acrylic, nylon or polyester, and can be formed by methods such as warp knitting, stitch bonding or needle punching. Suitable loop materials are available from Guilford Mills, Inc., Greensboro, N.C., U.S.A. under the trade designation No. 36549. Another suitable loop material can comprise a pattern un-bounded web as disclosed in U.S. Pat. No. 5,858,515 issued Jan. 12, 1999 to Stokes et al.
Hook type fasteners typically comprise a fabric or material having a base or backing structure and a plurality of hook members extending upwardly from at least one surface of the backing structure. In contrast to the loop type fasteners which desirably comprise a very flexible fabric, the hook material advantageously comprises a more resilient material to minimize unintentional disengagement of the fastener components as a result of the hook material becoming deformed and catching on clothing or other items. The term xe2x80x9cresilientxe2x80x9d as used herein refers to an interlocking material having a predetermined shape and the property of the interlocking material to resume the predetermined shape after being engaged and disengaged from a mating, complementary interlocking material. Suitable hook material can be molded or extruded of nylon, polypropylene or another suitable material. Hook materials are available from commercial vendors such as Velcro Industries B.V., Amsterdam, Netherlands or affiliates thereof, including specific materials identified as Velcro HTH-829 with a uni-directional hook pattern and having a thickness of about 0.9 millimeters (35 mils) and HTH-851 with a uni-directional hook pattern and having a thickness of about 0.5 millimeters (20 mils); and Minnesota Mining and Manufacturing Co., St. Paul, Minn. U.S.A., including specific materials identified as CS-600.
Hence, in another embodiment, the invention concerns a method of unwinding a mechanical fastener material. The method includes providing a roll of mechanical fastener material comprising a base and a plurality of engaging elements projecting from the base. The mechanical fastener material defines at least 3 lanes containing engaging elements with integral separators disposed between the lanes. The lanes can have a width of about 5 cm. or less. The method also includes tearing the mechanical fastener material along a separator to disconnect at least one lane from a plurality of other lanes, and unwinding the one lane from the roll while continuing to tear the mechanical fastener material along the separator. The plurality of other lanes are maintained on the roll while the one lane is unwound.
In particular embodiments the web material can comprise a hook material. The multiple lane configuration can be produced in-line in the hook production process. The parent rolls can be produced in relatively wide widths, for example from about 7 to about 100 cm. depending on the manufacturer""s width constraints and tension tolerances. In one particular embodiment, by way of illustration, the web material can be divided into lanes having a width of about 1.3 cm. with separators disposed between the lanes. The separators can comprise longitudinal channels or splitting lanes of reduced thickness. For example, the base of the hook material can have a nominal thickness of about 0.3 millimeters (mm.) and the separators can have a nominal thickness at their center of about 0.05 mm. The separators can be very narrow, such as on the order of about 0.2 mm. Alternatively, the web material can comprise loop material or other mechanical fastening material.
In another aspect, the present invention also concerns an apparatus for unwinding a roll of web material having first and second integral lanes. The apparatus includes at least one roll unwind stand comprising a shaft defining an unwind axis and a drive mechanism adapted to rotate the shaft. A repositioning device, which is adapted to redirect a lane as it is unwound, is movably mounted and positionable at a plurality of positions along an axis generally parallel to the unwind axis. The plurality of positions correspond to different lane positions. The apparatus also includes a control system adapted to: move the repositioning device to a first location corresponding to at least one first lane, rotate the drive mechanism to unwind the at least one first lane, move the repositioning device to a second location corresponding to at least one second lane, and rotate the drive mechanism to unwind the at least one second lane. The second lane can remain on the roll while the fist lane is unwound.
The apparatus can also employ sensors that provide roll diameter information. Thus, in another embodiment, an apparatus for unwinding rolls of web material having a plurality of integral lanes can comprise first and second roll unwind stands. The unwind stands comprise shafts defining unwind axes and one or more drive mechanisms adapted to rotate the shafts. A repositioning device is associated with each roll unwind stand and is adapted to redirect a lane as it is unwound. The repositioning devices are movably mounted and positionable at a plurality of positions along an axis generally parallel to the respective unwind axis. The plurality of positions correspond to different lane positions. A sensing device is associated with each roll unwind stand and is adapted to provide roll diameter information. The sensing devices are movably mounted and positionable at a plurality of positions along an axis generally parallel to the respective unwind axis. Again, the plurality of positions correspond to different lane positions. The apparatus also includes a control system adapted to: move the repositioning and sensing devices of the first roll unwind stand to a first location corresponding to at least one first lane, rotate the drive mechanism of the first roll unwind stand to unwind the at least one first lane, move the repositioning and sensing devices of the first roll unwind stand to a second location corresponding to at least one second lane, rotate the drive mechanism of the first roll unwind stand to unwind the at least one second lane, move the repositioning and sensing devices of the second roll unwind stand to a first location corresponding to at least one first lane, rotate the drive mechanism of the second roll unwind stand to unwind the at least one first lane, move the repositioning and sensing devices of the second roll unwind stand to a second location corresponding to at least one second lane, and rotate the drive mechanism of the second roll unwind stand to unwind the at least one second lane. The second lanes can remain on their corresponding rolls while the first lanes are unwound.
In particular embodiments, the sensing devices can detect the position of the next lane to be unwound. Further, the control system can use sensor feedback information to control the position of the repositioning devices.
The apparatus as described herein can be used to unwind a roll of web material having first and second integral lanes, including the steps of: positioning a repositioning device at a first position corresponding to the position of the first lane, where the repositioning device is adapted to redirect a lane as it is unwound; initiating separation of the first lane from the integral second lane; feeding the first lane onto the repositioning device; rotating the roll to unwind the first lane while tearing the first lane from the second lane and maintaining the second lane on the roll; moving the repositioning device to a second position corresponding to the position of the second lane; feeding the second lane onto the repositioning device; and rotating the roll to unwind the second lane.
The present invention facilitates high-speed manufacturing of products such as absorbent articles, including diapers, training pants, incontinence products, diaper pants, feminine care products, swim pants, disposable underwear, or the like. The multiple lane configuration of the web material is particularly suited for use with production of such garments, which often employ two or more pieces formed of narrow web material such as mechanical or adhesive fasteners. In manufacturing such garments, it can be advantageous to unwind a single lane of web material and subsequently tear or cut the single lane into two or more individual strips. The strips can then be cut and applied to the garment so that there are two fasteners per product.
Particular training pants suitable for use with the present invention are disclosed in U.S. patent application Ser. No. 09/444,083, filed on Nov. 22, 1999 (corresponding to PCT application WO 00/37009 published Jun. 29, 2000) by A. Fletcher et al. and titled xe2x80x9cAbsorbent Articles With Refastenable Side Seams;xe2x80x9d which is incorporated herein by reference. This reference describes various materials and methods for constructing training pants. Other methods and apparatus concerning the manufacture of training pants are disclosed in U.S. Pat. No. 4,940,464 issued Jul. 10, 1990 to Van Gompel et al.; and U.S. Pat. No. 5,766,389 issued Jun. 16, 1998 to Brandon et al.; which are also incorporated herein by reference.
The above-mentioned and other features and advantages of the present invention and the manner of attaining them will become more apparent, and the invention itself will be better understood by reference to the drawings and the following description of the drawings.
Within the context of this specification, each term or phrase below will include the following meaning or meanings.
xe2x80x9cBondedxe2x80x9d refers to the joining, adhering, connecting, attaching, or the like, of two elements. Two elements will be considered to be bonded together when they are bonded directly to one another or indirectly to one another, such as when each is directly bonded to intermediate elements.
xe2x80x9cComprisingxe2x80x9d is inclusive or open-ended and does not exclude additional, unrecited elements or method steps.
xe2x80x9cConnectedxe2x80x9d refers to the joining, adhering, bonding, attaching, or the like, of two elements. Two elements will be considered to be connected together when they are connected directly to one another or indirectly to one another, such as when each is directly connected to intermediate elements.
xe2x80x9cDisposablexe2x80x9d refers to articles which are designed to be discarded after a limited use rather than being laundered or otherwise restored for reuse.
xe2x80x9cDisposed,xe2x80x9d xe2x80x9cdisposed on,xe2x80x9d and variations thereof are intended to mean that one element can be integral with another element, or that one element can be a separate structure bonded to or placed with or placed near another element.
xe2x80x9cElasticxe2x80x9d xe2x80x9celasticizedxe2x80x9d and xe2x80x9celasticityxe2x80x9d mean that property of a material or composite by virtue of which it tends to recover its original size and shape after removal of a force causing a deformation.
xe2x80x9cFabricsxe2x80x9d is used to refer to all of the woven, knitted and nonwoven fibrous webs.
xe2x80x9cFlexiblexe2x80x9d refers to materials which are compliant and which will readily conform to the general shape and contours of the wearer""s body.
xe2x80x9cForcexe2x80x9d includes a physical influence exerted by one body on another which produces acceleration of bodies that are free to move and deformation of bodies that are not free to move. Force is expressed in grams per unit area.
xe2x80x9cIntegralxe2x80x9d is used to refer to various portions of a single unitary element rather than separate structures bonded to or placed with or placed near one another.
xe2x80x9cLayerxe2x80x9d when used in the singular can have the dual meaning of a single element or a plurality of elements.
xe2x80x9cMemberxe2x80x9d when used in the singular can have the dual meaning of a single element or a plurality of elements.
xe2x80x9cNonwovenxe2x80x9d and xe2x80x9cnonwoven webxe2x80x9d refer to materials and webs of material which are formed without the aid of a textile weaving or knitting process.
xe2x80x9cSurfacexe2x80x9d includes any layer, film, woven, nonwoven, laminate, composite, or the like, whether pervious or impervious to air, gas, and/or liquids.
These terms may be defined with additional language in the remaining portions of the specification.